Effects of storage up to 1 year on the in vitro antimicrobial activity of preformulated antibiotic‐impregnated calcium sulfate beads

Abstract

ObjectiveTo compare antimicrobial activity as demonstrated by the zone of inhibition (ZOI) produced by antibiotic‐impregnated calcium sulfate (CaSO4) beads after storage for 0, 3, 6, 9, and 12 months.Study designControlled laboratory study.Sample populationThree‐millimeter diameter CaSO4 beads impregnated with vancomycin (125 mg/mL), or amikacin (250 mg/mL), or without antibiotic (control).MethodsCalcium sulfate beads were created at the onset of the study. Individual beads were separated in sterile containers and stored in a closed cabinet at room temperature and humidity for 0, 3, 6, 9, or 12 months until testing. The ZOI against methicillin‐resistant Staphylococcus pseudintermedius, methicillin‐resistant Staphylococcus aureus, and Pseudomonas aeruginosa was recorded with serial replating on a fresh lawn of bacteria every 24 h until beads failed to produce a ZOI. The ZOIs and their changes were compared with mixed‐effects linear models. Eluted concentrations of vancomycin measured with high‐performance liquid chromatography were reported.ResultsAt 24 h, ZOIs were comparable regardless of time since formulation, except vancomycin against P. aeruginosa, which failed to generate a ZOI. The daily changes of ZOI and duration of activity of antibiotics did not vary between storage length (p > .05). There was no consistent change in eluted drug concentration between storage length of beads.ConclusionLight protected storage at room temperature for up to 12 months did not impair the in vitro activity of antibiotic‐impregnated CaSO4 beads, as demonstrated through ZOIs.Clinical significanceWhen stored correctly, antibiotic‐impregnated CaSO4 beads can be used at least up to 12 months after formulation.

Amikacin in 30% poloxamer 407 is a versatile local therapy with method of application and outcome documented in 29 dogs

“…10 The clinical use of vancomycin in P407 in complex orthopedic implant-related surgery complications has recently been reported with clearance of infection in 26 out of 34 dogs. 11 While CSH beads can be premade 26 and to date have been the most often used clinical delivery method for antibiotics in orthopedic surgery, some superficial wounds might not lend themselves well for CSH bead application. The efficacy, ease of use, and inexpensive nature of P407 warrant its further investigation as a topical delivery agent for antibiotics in both open and closed wound applications.…”